title: Plastid DNA sequencing and nuclear SNP genotyping help resolve the puzzle of central American Platanus.
abstract: OBJECTIVE
  Recent research on the history of Platanus reveals that hybridization phenomena occurred in the central American species. This study has two goals: to help resolve the evolutive puzzle of central American Platanus, and to test the potential of real-time polymerase chain reaction (PCR) for detecting ancient hybridization.
  
  
  METHODS
  Sequencing of a uniparental plastid DNA marker [psbA-trnH((GUG)) intergenic spacer] and qualitative and quantitative single nucleotide polymorphism (SNP) genotyping of biparental nuclear ribosomal DNA (nrDNA) markers [LEAFY intron 2 (LFY-i2) and internal transcribed spacer 2 (ITS2)] were used.
  
  
  RESULTS
  Based on the SNP genotyping results, several Platanus accessions show the presence of hybridization/introgression, including some accessions of P. rzedowskii and of P. mexicana var. interior and one of P. mexicana var. mexicana from Oaxaca (= P. oaxacana). Based on haplotype analyses of the psbA-trnH spacer, five haplotypes were detected. The most common of these is present in taxa belonging to P. orientalis, P. racemosa sensu lato, some accessions of P. occidentalis sensu stricto (s.s.) from Texas, P. occidentalis var. palmeri, P. mexicana s.s. and P. rzedowskii. This is highly relevant to genetic relationships with the haplotypes present in P. occidentalis s.s. and P. mexicana var. interior.
  
  
  CONCLUSIONS
  Hybridization and introgression events between lineages ancestral to modern central and eastern North American Platanus species occurred. Plastid haplotypes and qualitative and quantitative SNP genotyping provide information critical for understanding the complex history of Mexican Platanus. Compared with the usual molecular techniques of sub-cloning, sequencing and genotyping, real-time PCR assay is a quick and sensitive technique for analysing complex evolutionary patterns.
authors.affiliation: Dipartimento di Biologia, Università degli Studi di Napoli Federico II, Via Foria 223, Orto Botanico, 80139 Napoli, Italy. olga.decastro@unina.it
authors.forename: Olga
authors.initials: O
authors.lastname: De Castro
authors.forename: Antonietta
authors.initials: A
authors.lastname: Di Maio
authors.forename: José Armando
authors.initials: JA
authors.lastname: Lozada García
authors.forename: Danilo
authors.initials: D
authors.lastname: Piacenti
authors.forename: Mario
authors.initials: M
authors.lastname: Vázquez-Torres
authors.forename: Paolo
authors.initials: P
authors.lastname: De Luca
mesh_terms: D001483:Base Sequence; D002489:Central America; D017343:Genes, Plant; D005838:Genotype; D005843:Geography; D006824:Hybridization, Genetic; D008969:Molecular Sequence Data; D018087:Plastids / Q000235:genetics*; D020641:Polymorphism, Single Nucleotide; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D014197:Trees / Q000235:genetics*
keywords: Central America; LEAFY intron 2; Platanus; SNP; genotyping; hybridization; internal transcribed spacer 2; introgression; psbA-trnH(GUG) intergenic spacer; real-time PCR; sequencing